0

I am making a shutter for my camera using a Arduino and an optocoupler.

I understand most of most parts, but unsure about the resistor because I don't have the correct size. 5V will be coming from the Arduino, and the 4N35 will need 1.3V 10mA. This leads to a 380Ω resistor.

Now I only have 100Ω, 220Ω, 330Ω, and 1kΩ resistors. I have read I shouldn't use anything lower than 380Ω and only use higher but 1kΩ seem a little too high haha.

Just looking for some pointers please.

1

1kΩ will be just fine. But if you want lower you could take two 1kΩ and place them in parallel - that will give you 500Ω.

BTW - 1kΩ will give you ((5-1.3)/1000=) 3.7mA through the diode of the optocoupler, and 500Ω will give you ((5-1.3)/500=) 7.4mA.

1
  • Thank you, works perfectly. Still got a lot of learning to do haha. – Stephen Mottershead Jan 9 at 18:03
1

And 330 will give you just over 11mA, I'd go with that

1
  • Agreed, absolute max current for 4N35 is IF < 50 mA. But if IF= 3.7 mA works reliably, as there's no current required on the output side, I'd take that. – DataFiddler Jan 10 at 12:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.